Apparatus, method, and system for roadway lighting using solid-state light sources

ABSTRACT

Disclosed herein are apparatus, methods, and systems for illuminating roadways, paths, tunnels, bridges, and areas adjacent to such in a manner which minimizes glare and/or other adverse lighting effects commonly experienced by night-time drivers. According to aspects of the invention, horizontal and vertical aiming of a plurality of solid-state light sources permits projected light from a fixture to be tailored to roadway features (e.g., bends in the road) and in some cases, permits the mounting height of fixtures to be reduced which can make the envisioned system a cost-effective alternative to traditional roadway lighting.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of Ser. No. 12/887,595filed Sep. 22, 2010, now U.S. Pat. No. 8,517,566 issued Aug. 27, 2013,which claims priority under 35 U.S.C. §119(e) of provisional applicationSer. Nos. 61/246,033 filed Sep. 25, 2009 and 61/254,945 filed Oct. 26,2009, which applications are hereby incorporated by reference in theirentireties.

This application also claims benefit under 35 U.S.C. §120 to U.S.application Ser. No. 12/751,519, filed Mar. 31, 2010, now U.S. Pat. No.8,449,144 issued May 28, 2013, which is hereby incorporated by referencein its entirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to the illumination of roadwaysat night. More specifically, the present invention relates to the use ofsolid-state light sources in roadway lighting as a way to improve overstate of the art roadway lighting.

The adequate illumination of roadways is known to be problematic,particularly because of the competing interests in designing roadwaylighting systems. For example, one usually seeks to minimize the cost ofa lighting system (both capital and operating) but must also considersuch things as glare, lighting uniformity, and other parameters whichare well known in the art and regulated by the industry; BritishStandard (BS) 5489-1:2003 and Illuminating Engineering Society (IES)RP-8-00 are but two examples of the standards and codes which governroadway lighting design.

To better understand the conflicting design interests, some discussionof how roadway lighting impacts a driver is warranted. As is well known,a roadway is typically illuminated by a plurality of light fixtureselevated and generally positioned above the roadway by a supportstructure (also referred to as a pole). Each fixture typically includesa single light source (e.g., metal halide (MH) or high pressure sodium(HPS)) and some form of optic (e.g., reflector, visor, lens, etc.) toprovide limited control of the light projected therefrom. Each elevatedfixture is aimed generally downward and located a significant distancefrom the next elevated fixture (e.g., on the order of seven times themounting height) so to illuminate a significant stretch of road (alsoreferred to as a carriageway).

As is well known, a night-time driver has specific vision requirementsto ensure maximum visibility and driver safety. The typical night-timedriver requires a minimum luminous intensity to perform the visual task(e.g., perceive objects on the roadway, respond to signage, maneuverbetween lanes, etc.) and a minimum contrast to distinguish betweenobjects and the background; this is particularly true for objects in adriver's periphery as a night-time driver is (i) less able to perceivecontrast than a daytime driver and (ii) less able to perceive contrastfor objects that are not in detail (objects in one's periphery typicallybeing in less focus than objects directly in one's line of sight).

So as an example, the cost of a roadway lighting system could be reducedby reducing the mounting height of the lighting fixtures; however, ifthe fixtures are lowered enough that a driver can directly see the lightsource, the perceived brightness of the light source can diminish thedriver's ability to perceive contrast and, if the driver views the lightsource for a prolonged period, cause the driver's eyes to adapt to thebrighter source and thus, have insufficient luminous intensity (alsoreferred to as illumination or light level) for the visual task.

As another example, adding additional poles with corresponding fixturesto a roadway lighting system could reduce or eliminate areas ofinsufficient luminous intensity (i.e., improve the lighting ofpoorly-lit areas), thereby improving lighting uniformity and drivervisibility; however, this would greatly increase the cost of thelighting system as it is well known that the cost of a support structurecan equal that of the fixture itself, if not exceed the cost of thefixture. Alternatively, additional fixtures could be added to theexisting poles and aimed at portions of the roadway with lower lightlevels; however, adding fixtures to an existing pole is no simple task.Since traditional light sources are large and the fixtures are aimedgenerally downward, introduction of additional fixtures aimed at variousangles requires large visors to provide a desired cutoff so to preventglare and other adverse lighting conditions already described. Care mustbe taken so that one fixture's cutoff does not adversely affect anotherfixture's cutoff. Further, a pole must be substantial enough to bothprovide the surface area for affixing the new fixtures and withstandanticipated wind loading.

Of course, some roadway lighting applications cannot make use of largesupport structures. For example, on bridges and in tunnels fixtures aretypically mounted to walls, dividers, medians, or other existingstructural features at or near the estimated eye height of a driver.Said fixtures cannot be aimed generally downward and provide adequateillumination of the roadway and so are aimed at a shallow angle;however, the aiming angle must be carefully selected so to avoid beingdirectly viewable by the driver (the dangers of which have beendescribed). One proposed solution is to combine the low mounting heightwith directional illumination (e.g., fixtures aimed so to project lightin the direction a vehicle is traveling). One example is the MIRTRAN™system commercially available from MUSCO® Lighting of Oskaloosa, Iowa,USA and commonly used to illuminate racetracks; see also U.S. Pat. Nos.5,402,327, 5,647,661, and 6,220,726. Systems like MIRTRAN™ meet thestrict needs of racecar driving (e.g., very high speeds, color and lightlevels in accordance with television broadcast requirements, etc.) butare somewhat overspecialized for traditional roadway lighting; further,systems like MIRTRAN™ still employ a single, large light source withlimited control of the light projected therefrom.

So it can be seen that the current state of the art of roadway lightingis limited by conflicting design factors. The art would benefit fromapparatus and methods for adequately illuminating a roadway in a mannerthat does not adversely affect a driver's visibility but also maintainscost-effectiveness. Thus, there is room for improvement in the art.

SUMMARY OF THE INVENTION

The emergence of light emitting diodes (LEDs) and other solid-statedevices as increasingly affordable light sources offers the potentialfor use in roadway lighting, particularly because a plurality of saidlight sources can be contained in a single fixture but controlledindependently; this permits customization of light projected therefromfar beyond what is possible and/or cost-permissible using traditionallight sources.

Envisioned are apparatus, methods, and systems whereby a plurality ofsolid-state light sources in a fixture may be aimed, collimated, orotherwise controlled so to suitably illuminate a roadway (or the like)while preserving driver visibility, and in a manner that providesbenefits beyond merely increasing the number of light sources in afixture. Beyond the benefit of increased aiming capabilities which, forexample, allows light to be projected according to a complex beampattern, some subset of the solid-state light sources could be ofdiffering color properties so to aid in improving visibility duringparticular environmental conditions. Further, said light sources couldbe controlled remotely such that they can be selectively turned on, off,or dimmed, for example, according to need or preference. As is wellknown in the art, traditional light sources (e.g., HPS, MH, etc.) aresomewhat limited in their selectable color properties and requiresignificant time to reach maximum luminous output after being turnedoff, thereby limiting their effectiveness in responding to changingdriving conditions.

It is therefore a principle object, feature, advantage, or aspect of thepresent invention to improve over the state of the art and/or addressproblems, issues, or deficiencies in the art.

Further objects, features, advantages, or aspects of the presentinvention may include one or more of the following:

-   -   a. apparatus and methods for adequately illuminating a roadway,        path, bridge, tunnel, parking lot, or areas adjacent to such        during periods of reduced visibility;    -   b. apparatus and methods for minimizing glare and/or other        adverse lighting effects commonly experienced by roadway        drivers; and    -   c. apparatus and methods for operating a solid-state light        source roadway lighting system such that cost-effectiveness may        be realized.

One system according to aspects of the present invention comprisesfixtures including a plurality of solid-state light sources, each ofwhich may be of selectable optical properties, aiming, color, or thelike. Said fixtures are elevated at or near driver eye height on abridge or in a tunnel, for example, and are designed so to (i)illuminate the roadway, (ii) provide a reference point for drivers, and(iii) greatly reduce or eliminate glare for the typical driver. It is ofnote that described herein glare is defined as any perceived brightnesswhich interferes with a driver's vision and is not limited to a type ofglare (e.g., discomfort glare) or a direction of viewing (e.g., directlyat the light source).

These and other objects, features, advantages, or aspects of the presentinvention will become more apparent with reference to the accompanyingspecification and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

From time-to-time in this description reference will be taken to thedrawings which are identified by figure number and are summarized below.

FIG. 1 diagrammatically illustrates illumination of a typical roadwayusing traditional lighting methods.

FIGS. 2A-C illustrate various methods of adjusting the aiming of roadwaylighting fixtures in the horizontal plane according to aspects of thepresent invention.

FIGS. 3A and B illustrate various methods of adjusting the aiming ofroadway lighting fixtures in the vertical plane according to aspects ofthe present invention.

FIGS. 4A and B diagrammatically illustrate illumination of a typicalroadway according to a first embodiment.

FIG. 4C illustrates a perspective view of an exemplary apparatus forproducing the illumination diagrammatically illustrated in FIGS. 4A andB.

FIG. 5A diagrammatically illustrates illumination of a typical roadwayaccording to an alternative embodiment.

FIG. 5B illustrates a perspective view of an exemplary apparatus forproducing the illumination diagrammatically illustrated in FIG. 5A; forclarity, bolts and analogous components have been removed.

FIGS. 5C-E illustrate features of the alternative exemplary apparatusaccording to Detail A of FIG. 5B. FIG. 5C illustrates, in particular,one form of connector 201.

FIG. 5D illustrates, in particular, an alternative form of connector201. FIG. 5E illustrates in enlarged exploded perspective view thecomponents between plate 209 and housing 211.

FIGS. 5F and G illustrate, in a section view taken transversely throughthe part and viewed along line A-A of FIG. 5B, two possible orientationsof visor 202 and housing 211.

FIGS. 6A and B illustrate exploded perspective views of two exemplaryLED assemblies.

FIGS. 6C-E illustrate various views of outer lens 301, reflector 302,and holder 304, respectively, used in the two exemplary LED assembliesof FIGS. 6A and B.

FIGS. 7A-E illustrate various views of two forms of an end cap 400 foruse with plate 209 and housing 211 according to FIG. 5E.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A. Overview

To further an understanding of the present invention, specific exemplaryembodiments according to the present invention will be described indetail. Frequent mention will be made in this description to thedrawings. Reference numbers will be used to indicate certain parts inthe drawings. The same reference numbers will be used to indicate thesame parts throughout the drawings.

The exemplary embodiments envision apparatus, methods, and systems whichemploy a plurality of highly controlled solid-state light sources toadequately illuminate a roadway, path, bridge, tunnel, parking lot, orareas adjacent to such in a manner that reduces glare, diminishes theeffects of conditions that reduce visibility, improvescost-effectiveness when compared to traditional lighting systems, and isadapted for remote control. As described herein, apparatus, methods, andsystems make use of LEDs for roadway lighting; however, other lightsources (e.g., lasers) and other applications (e.g., racetracks) arepossible, and envisioned.

A typical roadway lighting system may generally be characterized withrespect to FIG. 1. As can be seen, a vehicle 1 travels along a roadway 2illuminated by lighting fixtures 10; it is of note that, as illustrated,travel in both lanes on either side of median 4 (also referred to as acentral reservation) is in the same direction and indicated by arrows.As previously stated, fixtures 10 comprise a single HPS or MH lightsource-typically rated for operation at 150-250 W—and are aimed in adownward fashion so to illuminate the area generally below the fixture.The spacing between and the mounting height of fixtures 10 depends on avariety of factors (see, for example, European Standard EN 5489-1:2003),but for the system illustrated in FIG. 1 a mounting height of 12-15meters and a spacing between fixtures of 60-80 meters is common; thesignificant mounting height ensures a driver does not experience glarefrom directly viewing the light source. However, the combination of thesignificant mounting height, spacing between, and generally downwardaiming of the fixtures leads to well-lit areas 21 of roadway 2 with morepoorly illuminated sections 5 interposed. As is well known in the art,illumination such as that diagrammatically illustrated in FIG. 1 isundesirable for night-time driving because of the accommodation reflexof the human eye; namely, when a driver approaches well-lit areas 21 thepupil contracts quickly but when the driver approaches poorly-litsections 5 the pupil is much slower to dilate and thus, visibility isdiminished.

One approach described herein is to change the way in which fixtures areaimed in the horizontal plane. For example, FIGS. 2A and B illustratetwo lanes of traffic flowing in the same direction similar to thatillustrated in FIG. 1. To control the amount of glare a driverexperiences, horizontal beam control from a fixture 1000 is such thatedge 70 of the beam is projected at an angle generally forward of thedriver (see FIG. 2A) or at a nearly right angle to the driver (see FIG.2B) so the light source is not in direct view of the driver. Likewise,edge 72 is projected at an angle forward of the driver (e.g., on theorder of 20 degrees) so the light source is not in direct view of thedriver via the rearview mirror. Of course, if it is desirable to havesome light directed towards oncoming traffic, edge 70 could berestricted to a few degrees further toward the driver; this isillustrated in FIG. 2C. This approach permits the mounting height offixtures 1000 to be reduced (e.g., on the order of severalmeters)—thereby reducing the cost to illuminate roadway 2—withoutincreasing glare for traffic flowing in a single direction.

Another approach described herein is to change the way in which fixturesare aimed in the vertical plane. For example, FIG. 3A illustrates onelane of traffic as perceived by a driver in the lane. To control theamount of glare a driver experiences, vertical beam control from afixture 1000 is such that bottom edge 62 of the beam is projected at anangle generally downward from fixture 1000 (e.g., on the order of 45degrees down from horizontal) so to illuminate the area directly infront of fixture 1000. Top edge 60 of the beam projected from fixture1000 is aimed so to strike vehicle 1 just below the window (i.e., justbelow the average driver's eye height-meaning the position of a typicaldriver's eyes above the roadway surface when operating a vehicle alongthe roadway); the center of the beam (i.e., what is generally acceptedas its brightest point) typically strikes vehicle 1 much lower (e.g.,near the top of the wheels), though this is a function of thepositioning of a visor or other light-directing apparatuses.

The exact angle of top edge 60 relative to the mounting height offixture 1000 and where top edge 60 strikes vehicle 1 can vary dependingon a variety of factors. For example, the average driver's eye height is1.08 meters (3.5 feet) above the roadway surface for passenger cars and2.4 meters (8.0 feet) for light trucks and vans (American Association ofState Highway Transportation Officials, A Policy on Geometric Design ofStreets and Highways (2001), sometimes called the AASHTO “Green Book”).Actual driver's eye height can vary from vehicle to vehicle (e.g., ishigher in an over-the-road truck than a compact car) and person toperson (e.g., is higher for taller persons). Regardless, a driver's eyeheight is substantially less than the typical 12-15 meter mounting (ormore) height for typical pole-mounted street or roadway lights) and istypically lower than the maximum vertical height or dimension of thevehicle being driven. Of course, most roadways are adapted for a varietyof vehicles of different sizes, including maximum vertical height ordimension. Though there is a typical range of such maximum dimensions,the term as used herein is not limited to any one height, but isintended to convey the idea of monitoring height on the order of the eyeheight of drivers in typical automobiles (cars and trucks) traversingthe particular roadway.

Given the numerous factors involved with vertical aiming, it may bepreferable to design for a known height. For example, depending on thenumber of lanes in roadway 2, it may be necessary to provide fixtures1000 on both sides of the road so to adequate illuminate the entirewidth of roadway 2; this is generally illustrated for a divided roadwayin FIG. 3B. As can be seen in FIG. 3B, top edge 60 of the beam projectedfrom each fixture 1000 is aimed so to strike the top edge of a pole onthe other side of the lane (of course, concrete dividers, guardrails, orthe like could be used in place of poles); this still eliminates glarefor the majority of drivers, as the typical pole height in this exampleis on the order of one meter (e.g., a typical concrete divider is on theorder of eighty centimeters). So for the example in FIG. 3B, a designerwould know the width of roadway 2 and the height of the pole and thus,would easily be able to determine the desired vertical aiming angle offixture 1000 so to produce appropriate edges 62 and 60.

Thus, as can be seen and appreciated by one in the art, the angles ofbeam edges 60, 62, 70, and 72 relative to vehicle 1 depends on thesetback of fixture 1000 relative to roadway 2, the number of lanes, thewidth of lanes, the height of each fixture 1000, and the like. As such,a preferred embodiment includes one or more of an adjustable visor orother optic, a plurality of pivotable LEDs, and apparatus forpositioning the fixture; this permits significant aiming flexibilitysuch that the envisioned lighting system could be used to illuminatecomplex roadway features (e.g., bends in the road) without addingsignificant cost to the system. For example, as has been stated,traditional light sources are aimed generally downward from asignificant mounting height and the light projected therefrom not wellcontrolled; this limits the projected beam patterns to a relatively fewpossibilities (see, for example, Beam Types I-V as defined by theaforementioned IES and commonly used in roadway lighting design). Whileadequate for many roadway configurations, if a roadway had a complexfeature—a classic example being a cloverleaf interchange which is knownto be problematic to adequately illuminate—there are typically twosolutions; accept inadequate illumination or add additionalfixtures/poles. If the latter solution is accepted, not only is costadded to the system, but often the poorly controlled light spills overinto areas that do not need to be illuminated, wasting what wouldotherwise be useful light. Alternatively, selection of beam angles 60,62, 70, and 72 of fixture 1000 permits a designer to direct more lightat the target area which may reduce the number of fixtures needed toprovide adequate illumination.

B. Exemplary Method and Apparatus Embodiment 1

A more specific exemplary embodiment, utilizing aspects of thegeneralized example described above, will now be described. The presentembodiment utilizes concepts of adjusting how light is aimed in thehorizontal plane; of course, this does not preclude adjusting light inthe vertical plane as well.

FIG. 4A illustrates the general roadway scenario previously described inwhich a vehicle 1 travels along a roadway 2; is of note that asillustrated travel in both lanes on either side of median 4 is in thesame direction and indicated by arrows. As envisioned, fixtures 100 areaimed so to project light generally forward of vehicle 1 as previouslydescribed for fixtures 1000 (and illustrated in FIGS. 2A and B). Thespacing between fixtures 100 approximates that of current roadwaylighting fixtures (e.g., on the order of 60-80 meters), but becauselight is directed with traffic the mounting height is greatly reduced(e.g., reduced to a mounting height on the order of 3-6 meters).

In addition to projecting light in a manner that is not directlyviewable by the driver of vehicle 1, some subset of the LEDs in fixture100 may be aimed so to provide lighting to areas adjacent to roadway 2(see reference no. 20); the benefit of this is generally illustrated inFIG. 4B in which a driver of vehicle 1 may be able to see an object 3from a farther distance and/or sooner when adjacent areas 20 areilluminated, even if areas 20 are not as well illuminated as areas 21 interms of measured light levels. As previously discussed, illumination ofareas in the driver's periphery may greatly improve night-time drivingvisibility.

FIG. 4C illustrates fixture 100 as envisioned; as can be seen, fixture100 generally comprises a weather-tight housing 170 containing aplurality of LEDs 190 (e.g., model XP-E available from Cree, Durham,N.C., USA) each with its own optic 150 (in this example, a reflector)individually aimed and positionally affixed by a plate 160; housing 170being sealed by a transparent lens 180. Fixture 100 may include someapparatus or method of dissipating heat (as LED life and performance isknown to degrade with increasing heat); in this example, heatdissipation is achieved by aluminum housing and integral cooling fins130, though this is not by way of limitation. Fixture 100 could beaffixed to a pole or other support structure by a variety of apparatusor methods; in this example, a yoke may be affixed to fixture 100 viatapped and threaded holes 140 on either side of fixture 100, the yokebeing further affixed to the pole (see FIG. 4B). This particularapparatus or method of affixing fixture 100 to a pole permitsadjustability in two axes (a first axis through holes 140 and a secondaxis through the yoke's connection point to the pole) which is adequatefor most roadway lighting applications; however, adjustability about athird axis could be permitted depending on the selection of optics(e.g., diffusers) and/or by appropriate apparatus similar in function tothe yoke.

In practice, plate 160 could be punched, machined, or otherwise formedso to positionally affix optics 150 in a pattern suitable to achieve adesired beam pattern (see, for example, FIG. 4A); U.S. patent Ser. No.12/467,160 (now U.S. Pat. No. 8,356,916 issued Jan. 22, 2013)incorporated by reference herein discusses how the light projected fromfixture 100 can be adjusted by selective design of plate 160 to suit anapplication. Once fixture 100 is assembled with a customized plate 160,it may be affixed to a pole or other support structure via the yokeillustrated in FIG. 4A or an analogous component; refinements in aimingcan be performed by pivoting fixture 100 about the two axes previouslydescribed.

Of course, roadway conditions could change such that changes in fixture100 may be needed. For example, if roadway 2 is widened and existingLEDs 190 can still provide adequate illumination, then the only changemay be to re-aim fixture 100 via pivoting about one or more of theavailable pivot axes. If the shape of roadway 2 is changed and existingLEDs 190 can still provide adequate illumination, then a new beampattern could be developed and a new plate 160 installed in fixture 100.If, however, existing LEDs 190 cannot provide adequate illumination(e.g., increasing the power to existing LEDs would severely reduce theiroperating life), existing LEDs 190 could be switched out for morepowerful ones; this may require switching out optics 150 or creating anew plate 160 as well. If such changes are expected then it may bepreferable to modify fixture 100 such that each LED 190 may beindependently adjustable on site without having to produce a new plate160; U.S. patent Ser. No. 12/751,519 (now U.S. Pat. No. 8,449,144 issuedMay 28, 2013) incorporated by reference herein discusses apparatus forachieving such.

Alternatively, roadway conditions could change due to environmentalfactors. For example, inclement weather (e.g., sand storm, heavy rain,snow, sleet, etc.) which greatly diminishes visibility during daytime ornight-time driving could be addressed by envisioned fixture 100. Forexample, as is well known in the art of lighting the human eye typicallyhas three ranges of vision adaptability in which different parts of theeye are active: the photopic, mesopic, and scotopic ranges. In thephotopic range, illumination is relatively abundant (e.g., 30 lux) andthe cones of the eye (the part of the eye responsible for color and finedetail detection) are active. In the photopic range, the human eye isadapted such that yellow-green light is most perceivable. In thescotopic range, illumination is relatively scant (e.g., 0.1 lux) and therods of the eye (the part of the eye responsible for contrast andmovement detection) are active. In the scotopic range, the human eye isadapted such that blue light is most perceivable (though the coloritself is not detectable). The mesopic range lies between the photopicand scotopic ranges; both cones and rods are active in this range. Anight-time driver experiences primarily mesopic vision, though theadjacent areas of the roadway (where an animal or object may enter theroadway) and areas in the driver's periphery fall into the scotopicrange; as such, a bluish roadway light may be more preferable than ayellowish roadway light, particularly when driver safety is a concern.

However, light that is of a blue wavelength is known to scatter morethan light of a yellow wavelength due to interactions with variousparticles in the air (i.e., why the sky is perceived as blue); this,coupled with the eye's sensitivity to blue light during night-timedriving, may create a visual impairment in the event of an abundance ofparticles with which the light interacts (e.g., snow, sand, sleet, rain,etc.). As such, it may be preferable that, during a sand storm or snowstorm for example, a secondary fixture be used which is equipped withLEDs 190 that project light of a different color than the primaryfixture; this is generally illustrated in FIG. 4B in which a primaryfixture 100B illuminates roadway 2 during normal driving conditions anda secondary fixture 100A supplements fixture 100B during periods ofgreatly reduced visibility. Secondary fixture 100A is mounted close tothe ground (e.g., on the order of a meter) and aimed so to illuminatearea 21, not so much to increase the light level of area 21, but toprovide a reference point for the driver.

Control of secondary fixture 100A could be enabled on site (e.g., via amanually operated member), but that would likely limit the ability torapidly respond to changing roadway conditions. It would be beneficialfor secondary fixture 100A—and ideally the entire roadway lightingsystem—to be controlled remotely (at least as an alternative to on-sitecontrol); U.S. Pat. Nos. 6,681,110 and 7,778,635 both of which areincorporated by reference herein discuss apparatus and methods ofremotely controlling lighting systems. A sensor or analogous devicecould be installed on site and adapted to provide feedback to supplementthe envisioned remote control functionality; a photocell to indicateambient light levels or a commercially available weather alert sensor(e.g., any model of wireless weather station devices available fromRainwise, Bar Harbor, Me., USA) to indicate rainfall and barometricpressure are but two examples.

C. Exemplary Method and Apparatus Embodiment 2

An alternative embodiment envisions a roadway lighting system whichutilizes concepts of adjusting how light is aimed in the vertical plane;of course, this does not preclude adjusting light in the horizontalplane as well.

FIG. 5A illustrates a general roadway scenario in which four lanes oftraffic flow across a bridge, two lanes in each direction in accordancewith vehicles 1 and arrows projecting therefrom. As envisioned, fixtures200 are affixed to existing guardrails on the bridge, primarily toeliminate the cost of a support structure; this is achieved via abracket 203 and support arm 207 (see FIGS. 5B-D). As designed, bolts 204extend through aperture 205 in bracket 203 and aperture 206 in arm 207and are secured by a nut or analogous component (not illustrated). Arm207 is fixed to fixture 200 (e.g., by bolts 216 and/or other methodsincluding but not limited to screws, rivets, welding, and adhesives).Aperture 206 is purposefully sized to allow for curvature or unevennessof the guardrails, though this is by way of example and not by way oflimitation. For example, if fixtures 200 were used to illuminate aroadway in a tunnel, fixture 200 could be bolted directly to the tunnelwall via bolt or analogous device through housing 213 and bracket/arm203/207 omitted from the design. Alternatively, if no existingstructural features were suitable, fixtures 200 could be mounted on aprovided pole in a fashion similar to that illustrated in FIGS. 3A andB. The exact length of fixtures 200 and the number of LEDs containedtherein can vary depending on the availability, size, and spacing ofexisting structural features such as guardrails, or according to someother need or preference. For example, FIG. 5B illustrates a singlefixture 200 containing two housings 211 each of which contains ten LEDassemblies 300; as envisioned, fixture 200 is three or more meters inlength with each housing 211 a meter or more in length, though this canvary depending on the needs of the application.

Each fixture 200 is joined to the next fixture via connector 201 toprovide a continuous string of lights along roadway 2; this ensures bothuniformity in lighting and provides a reference for indicating the edgeof roadway 2 (discussed later). The exact form of connector 201 dependson the position of fixture 200 in the assembled lighting system. Forexample, fixtures 200 at each end of the assembled lighting system areequipped with connector 201B (see FIG. 5D) so to prevent glare as avehicle approaches area 21 (see fixtures 200 in FIG. 5A); all interposedfixtures 200 are equipped with connector 201A (see FIG. 5C). Theinteraction between connector 201 and housing 213 is illustrated ingreater detail in FIGS. 5F and 5G, which are section views along lineA-A illustrated in FIG. 5B (i.e., a section view taken through theoutermost LED assembly 300 looking along the length of fixture 200).

Fixtures 200 are designed to be adjustable in the vertical plane viapivoting of housing 211 about its longitudinal axis; this is achievedvia movement of bolts 212 through apertures 214 in plate 209; FIG. 5E isan exploded view of the components between housing 211 and plate 209according to Detail A of FIG. 5B. As can be seen from FIG. 5E, housing211 is affixed to an end cap 400 via bolts 401 extending through end cap400, through sealing gasket 500, and into slots 220. End cap 400 ispositioned in plate 209 and positionally held by bolts 212 extendingthrough apertures 214. Loosening bolts 212 allows housing 211 to pivotabout an axis extending through the center circular void of plate 209and along the length of housing 211. As designed, pivoting of housing211 is limited only by the travel of bolts 212 in apertures 214; in thisexample housing 211 may pivot approximately 90 degrees (see FIGS. 5F andG), though this is by way of example and not by way of limitation.

A primary purpose of end cap 400 is to seal housing 211 on either endand, similar to connectors 201, the exact form of end cap 400 depends onits position within fixture 200. For example, as can be seen in FIG. 5Beach fixture 200 comprises two housings 211. The end of the two housingsclosest to each other (i.e., nearest the center of fixture 200) areequipped with end cap 400B (see FIGS. 7A and B). Surface 431 of end cap400B is in abutment with housing 211 and is adapted to receive wiring(not illustrated) associated with LEDs 190. Surface 430 of end cap 400Bprojects outward from housing 211 and is adapted to receive a cable grip(e.g., any model of PROGRESS® available from Agro, Hunzenschwil,Switzerland); as is well known in the art, a cable grip helps totransport wiring or other objects in/out of an enclosure whilemaintaining a seal and protecting against moisture and otherenvironmental conditions. Wiring (not illustrated) from LED assemblies300 in both housings 211 are run from the aforementioned cable grip intovoid 210 of fixture 200 (see FIGS. 5F and G), preferably encapsulated inconduit. As envisioned, void 210 of fixture 200 houses other electricalequipment (e.g., driver) associated with the operation of solid-statelight sources such as LEDs 190, void 210 being primarily shielded fromenvironmental conditions due to the construction of fixture 200.

Alternatively, the opposite ends of housings 211 (i.e., the ends nearestconnector 201) are equipped with end cap 400A (see FIGS. 7C-E). Surface432 of end cap 400A projects outward from housing 211 and is adapted toseat in the center circular void of plate 209. Surface 433 of end cap400A is in abutment with housing 211 and is adapted to receive aprotective vent (e.g., any model of PolyVent available from W.L. Goreand Associates, Newark, Del., USA); as is well known in the art, aprotective vent helps to prevent pressure buildup and contamination ofsealed enclosures.

LED assemblies 300 generally comprise an LED 190 (e.g., model XP-Eavailable from Cree, Durham, N.C., USA) mounted to a board 303, someform of optic, and an outer lens 301 which seals against housing 211 viabolts 305 (through apertures 330) into apertures 221 and a gasket (notillustrated) in channel 331 (see FIG. 6C) which bounds opening 222. FIG.6A illustrates an exploded view of one possible assembly 300A; in thisassembly the optic comprises a reflector 302. As can be seen from FIGS.6A and D, reflector 302 comprises a metalized portion 803 which shapesthe light projected from LED 190 into a generally elliptical beampattern, opaque portions 802 which may also be reflective but areprimarily designed to provide a desired cutoff, aperture 804 throughwhich LED 190 passes, and apertures 801 in posts 800 through which bolts700 pass. In practice, bolts 700 are threaded into channel 223 ofhousing 211 such that board 303 is compressed between housing 211 andreflector 302 via posts 800; this is illustrated in assembly 300 ofFIGS. 5F and 5G.

An alternative assembly 300B is illustrated in FIG. 6B; in this assemblythe optic comprises a total internal reflection (TIR) lens 306 (e.g.,any of the FCP Series available from Fraen Corporation, Reading, Mass.,USA) combined with a diffuser 900 (e.g., any of the LIGHT SHAPINGDIFFUSERS® available from Newport Corporation, Irvine, Calif., USA).Similar to assembly 300A, assembly 300B is designed to project agenerally elliptical beam; in this example, diffusion sheet 900 producesa 35×75° elliptical beam pattern. Diffuser 900 is positioned within aholder 304 via tabs 901 (see FIG. 6E), though this is by way of exampleand not by way of limitation. For example, a custom lens could bedesigned which would achieve the functionality of the combination oflens 306 and diffuser 900, thus allowing holder 304 to be omitted fromthe design. In practice, bolts 700 are threaded into channel 223 ofhousing 211 in a manner similar to that described for assembly 300A suchthat board 303 and TIR lens 306 is compressed between housing 211 holder304 via and posts 800.

Adjustability of LED assemblies 300 in the vertical plane issupplemented by a visor 202 (see FIGS. 5B-D and 5F and G) which servesto (i) provide a distinct cutoff when desired and (ii) direct some lightfrom LED assemblies 300 back into fixture 200 so to provide indirectlighting (i.e., lighting where the source is not in direct view of adriver) that serves as a reference point for drivers. As designed, acarriage screw 208 extends through slot 215 in visor 202 and is securedby a nut or analogous component (not illustrated), the length of slot215 defining the range of vertical travel of visor 202 (in this example,on the order of several centimeters). FIG. 5F illustrates visor 202fully lowered and leaving a gap 218 between visor 202 and upper housingportion 213D. Upper portion 213D (designed to structurally supportconnector 201 and form void 210) is affixed to housing portion 213C(designed to structurally reinforce fixture 200) and lower housingportion 213B (designed to form void 210), lower housing portion 213Bbeing further affixed to back housing portion 213A (designed to supportplate 209 and interface with bracket/arm 203/207). FIG. 5G illustratesvisor 202 when fully raised so to eliminate gap 218.

In practice, one could loosen bolts 212, pivot housing 211 so to adjustthe vertical aiming of LEDs 190, tighten bolts 212, loosen carriagebolts 208, adjust visor 202 so to provide a desired cutoff andsufficient indirect lighting, and tighten carriage bolt 208;alternatively, visor 202 could be adjusted prior to aiming LEDassemblies 300. Of course, care must be taken not to aim LEDs 190 suchthat light projects through slot 215 of visor 202 as the result would bestriations in area 21 (i.e., non-uniform lighting). After appropriateaiming of fixtures 200, operation of said fixtures could be enabled onsite and/or remotely as described in Exemplary Method and ApparatusEmbodiment 1.

D. Options and Alternatives

The invention may take many forms and embodiments. The foregoingexamples are but a few of those. To give some sense of some options andalternatives, a few examples are given below.

Apparatus and methods for adjusting horizontal aiming (as described inExemplary Method and Apparatus Embodiment 1) and vertical aiming (asdescribed in Exemplary Method and Apparatus Embodiment 2) of solid-statelight sources described herein could be applied to lighting systemsother than those intended for roadways, bridges, tunnels, parking lots,and areas adjacent to such. Further, apparatus and methods forhorizontal and vertical aiming may be combined in a single lightingsystem for such applications without departing from at least someaspects of the present invention.

Described herein are a variety of bolts, brackets, yokes, and otherdevices for fastening some portion of the present embodiment(s) to someother part of the present embodiment(s) or support structure; it is ofnote that apparatus and methods of fastening parts may differ from thosedescribed herein and not depart from at least some aspects of thepresent invention. For example, portions 213A-D of housing 213 could bewelded instead of bolted (as illustrated). Alternatively, housing 213could be machined or otherwise formed from a single part. As anotherexample, visor 202 could be positionally affixed using a clamp-typedevice instead of bolt 208 through slot 215. As still another example,fixtures 100 could be affixed to a pole or other support structure usinga similar apparatus to bolt/slot 208/215 rather than a yoke.

Also described herein is a plurality of LEDs as well as associatedoptics housed within a fixture. As has been stated, other solid-statelight sources could be used and not depart from at least some aspects ofthe present invention. Beyond that, though, the optics for said lightsources could be varied according to need (e.g., to project a beampattern of a particular size or shape). For example, one LED 190 coulduse a TIR lens whereas another could use a light reflecting or blockingtab/visor, and still another use a reflector. Of course, there are otheroptions for the light sources as well. For example, the solid-statelight sources could be any number of available colors, a fixture couldcomprise any number or type of solid-state light sources, and the lightsources themselves could be laid out in any formation within a fixture(e.g., in a spiral pattern); some of these options could be selected foraesthetic purposes in addition to achieving the benefits describedherein.

As has been stated, the envisioned roadway lighting system is designedto provide adequate lighting without impairing a driver's vision whilebeing a cost-effective alternative to traditional roadway lighting;cost-effectiveness is primarily achieved by reducing or eliminating thecost of mounting structures, however, there are other cost savings whichcould be realized according to aspects of the present invention. Forexample, it is well known that LEDs have a long operating life (e.g., onthe order of several thousand hours longer than a traditional MH or HPSlight source). This, combined with the higher efficacy of LEDs comparedto some traditional light sources (i.e., LEDs produce more luminousoutput per watt of power than some traditional light sources), makesLEDs a cost-effective alternative for roadway lighting. A controlcircuit would be connected to the fixtures to supply and control powerto the light sources (e.g., diagrammatically illustrated at FIG. 5A).

Additionally, remote control functionality of the envisioned lightingsystem may contribute to cost savings. For example, it is well knownthat LEDs are readily dimmable; the operation at a dimmed level, itself,provides cost savings. It is possible for a motion sensor or the like(e.g., FIG. 5A) to be included with the lighting system such thatfeedback from the sensor could be communicated (e.g., wired, wireless,or combination two-way communication) to the remotely located controlcenter (e.g., FIG. 5A)—or trigger an immediate response—to regulate thepower provided to the LEDs. So, for example, a stretch of road that doesnot typically receive traffic during the midnight hours could be dimmed;however, when a sensor associated with the system detects a vehicle,power to the lights could be gradually increased to provide the desiredillumination. The sensor could be placed a significant distance awayfrom illuminated areas 21 (e.g., ¼ km) if desired so that the increasein illumination would not be distracting to the driver.

What is claimed is:
 1. A lighting system for lighting one or more lanesof traffic on a road in an outdoor environment comprising: a. aplurality of lighting fixtures, each fixture comprising: i. a pluralityof solid-state light sources, each of which produces a light output; ii.a plurality of optical elements; iii. a housing containing saidplurality of solid-state light sources and optical elements and adaptedto shield said plurality of solid-state light sources and opticalelements from environmental conditions; iv. means for providingelectrical power to said plurality of solid-sate light sources, saidmeans adapted to wirelessly receive instruction to modify the electricalpower provided to the plurality of solid-state light sources; b. one ormore supporting structures to which the lighting fixtures are attached,the supporting structures adapted to shield said means for providingelectrical power from environmental conditions; c. one or more sensorsproximate the one or more lanes of traffic and adapted to measure atleast one factor related to the outdoor environment, the one or moresensors further adapted to wirelessly communicate the measurements; d. aremotely located control center, the control center adapted towirelessly instruct control of the electrical power provided to theplurality of solid-state light sources in response to either (i) userpreference or (ii) measurements from the one or more sensors.
 2. Thelighting system of claim 1 wherein the sensors measure any of: a.ambient light; b. barometric pressure; c. rainfall; d. presence of anobject on the road; e. speed of an object on the road; f. weatheralerts.
 3. The lighting system of claim 1 further comprising a pluralityof adjustable armatures, each adjustable armature having opposite endsand affixed at one end to a lighting fixture and at the opposite end tothe supporting structure, the adjustable armature adapted to provideadjustment of the lighting fixture relative the supporting structure soto adjust placement of the light output of the light sources containedtherein relative the lanes of traffic.
 4. The lighting system of claim 3wherein each solid-state light source has selectable color properties.5. The lighting system of claim 4 wherein a subset of the plurality oflighting fixtures has different color properties than the remaininglighting fixtures and wherein said subset of lighting fixtures areadjusted so to project the light output of the light sources containedtherein to an area adjacent the lanes of traffic.
 6. The lighting systemof claim 1 wherein at least one sensor is located remotely from thelighting fixture but proximate the lanes of traffic.
 7. The lightingsystem of claim 1 wherein the plurality of optical elements comprisessome combination of: a. diffuser; b. visor; c. lens.
 8. A method ofproviding economic and customized lighting of a roadway and adjacentareas comprising: a. determining a size and shape of a first target areaand determining an illumination level for the first target area; b.determining a size and shape of a second target area and determining anillumination level for the second target area; c. providing a pluralityof lighting fixtures adapted to selectively light the first target area,the second target area, or both target areas at the determinedillumination levels in response to a command; d. providing a command tothe plurality of lighting fixtures wherein the command is based, atleast in part, on feedback from one or more sensors adapted to detectone or more conditions related to the roadway.
 9. The method of claim 8wherein the one or more conditions comprises: a. reduced visibility atthe roadway; b. presence of an object on the roadway.
 10. The method ofclaim 8 wherein the first target area comprises a portion of the roadwayand wherein the second target area comprises an area adjacent to theroadway.
 11. The method of claim 8 further comprising determining adimmed illumination level for the first target area and wherein theplurality of lighting fixtures are further adapted to selectively lightthe first target area to the dimmed illumination level in response tothe command.
 12. The method of claim 8 wherein step a. further comprisesdetermining a color of illumination for the first target area andwherein step b. further comprises determining a color of illuminationfor the second target area, the color of illumination for the secondtarget area different than the color of illumination for the firsttarget area, and wherein the plurality of lighting fixtures are adaptedto selectively light the target areas at the determined illuminationlevel and color.